1. The Field of the Invention
The invention generally relates to the field of interventional cardiology. More specifically, the invention relates to interventional cardiology procedures that require the placing of a stent in a body lumen, such as a body lumen of a patient or animal. The present invention further relates to systems for providing embolic protection during placing of a stent in a body lumen.
2. The Relevant Technology
Human blood vessels often become occluded or blocked by plaque, thrombi, other deposits, or material that reduce the blood carrying capacity of the vessel. Should the blockage occur at a critical place in the circulatory system, serious and permanent injury, and even death, can occur. To prevent this, some form of medical intervention is usually performed when significant occlusion is detected.
Several procedures are now used to open these stenosed or occluded blood vessels in a patient caused by the deposit of plaque or other material on the walls of the blood vessel. Angioplasty, for example, is a widely known procedure wherein an inflatable balloon is introduced into the occluded region. The balloon is inflated, dilating the occlusion, and thereby increasing the intra-luminal diameter.
Another procedure is atherectomy. During atherectomy, a catheter is inserted into a narrowed artery to remove the matter occluding or narrowing the artery, i.e., fatty material. The catheter includes a rotating blade or cutter disposed in the top thereof. Also located at the tip are an aperture and a balloon disposed on the opposite side of the catheter tip from the aperture. As the tip is placed in close proximity to the fatty material, the balloon is inflated to force the aperture into contact with the fatty material. When the blade is rotated, portions of the fatty material are shaved off and retained with the interior lumen of the catheter. This process is repeated until a sufficient amount of fatty material is removed and substantially normal blood flow is resumed.
In another procedure, introducing a stent into the stenosed region to open the lumen of the vessel treats stenosis within the artery or other blood vessel. The stent typically includes a substantially cylindrical tube or mesh sleeve made from such material as stainless steel or Nitinol. The design of the material permits the diameter of the stent to be radially expanded, while still providing sufficient rigidity such that the stent maintains its shape once it has been enlarged to a desired size.
To place a stent, many medical devices are typically used. Once access to the inside of the arterial system is established, usually through the femoral artery, a guide catheter is inserted into the artery and the tip thereof is guided to a position just proximal to the stenosed region to be treated. This guide catheter serves the purpose of allowing other devices to rapidly be delivered to that position without each being carefully guided from the point of access, through the tortuous anatomy of the arterial system to the point of intervention.
Typically, a small diameter guidewire is then inserted through the guide catheter and guided to the point distal to the stenosed region. When guidewire access to the lesion is established, and if there is sufficient cross sectional area in the narrowed part of the lesion, a stent, mounted on a delivery device, is installed over the guidewire. When correctly placed within the stenosed region, the stent will then be deployed, propping open the vessel at that point.
Various types of stents are used in these cases, but a common one requires that the stent be deployed from, or expanded from, a compressed state by a balloon upon which it is mounted. The balloon is inflated from the proximal end of the delivery device to a high pressure, which both opens the stenosis and embeds the stent into the inner lumen of the vessel at that point.
Once the guidewire is placed, the guidewire is used as a guide for all of the other devices that are used in the procedure. These devices have an inner lumen through which the proximal end of the guidewire, which is outside of the body of the patient, is inserted. The device is then slid along the guidewire into the body, allowing the guidewire to guide the device to the required position in the vascular system. The process of sliding another device over the guidewire is commonly known as an exchange.
Two basic types of devices facilitate exchanging of stent systems and dilation balloons. The first type of device encloses a guidewire within an inner lumen of the device for the entire length of the device. The second type of device only encloses the guidewire for a small distal segment of the device, with the remainder of the guidewire exiting from the inner lumen of the device through a side hole to allow the device and the guidewire to be side by side. In both cases, control of the guidewire is paramount during the exchange as the correct positioning of the device is reliant upon maintaining the position of the guidewire; this being difficult as at least a section of the guidewire is inaccessible due to it being enclosed in the inner lumen of the device being exchanged.
Providing a stent delivery device that reduces the complexity of an interventional procedure would advance the art of stent delivery. Furthermore, reducing the number of devices used to perform a stent implanting procedure would advance the art of stent delivery.
In addition, when these interventional procedures are performed, embolic particles may break off, flow down-stream, and cause potential adverse events. Devices are emerging that are designed to catch or filter these particles to prevent their downstream flow, to occlude the vessel during the intervention, and then allowing the particles to be aspirated out before they may flow downstream.
Current technology for embolic protection devices requires that they be delivered in a sheath distal to the point of intervention. This requires crossing the lesion with a large-diameter, relatively stiff device that is itself a potential embolic event that may occur before the embolic protection device is in place. The sheath must then be removed allowing the filter to be deployed in the vessel. After the device is deployed, balloons, stents, or other therapies of choice may be exchanged over the device to treat the area of interest. When the procedure is completed, the embolic protection device is captured by another catheter that is exchanged over the embolic protection device capturing any potential embolic material within it. This relatively complicated procedure adds complexity to providing stenting and other procedures.
The device and methods described herein are meant to overcome deficiencies of the current devices allowing quicker, safer and easier protection and stenting procedures to be undertaken.